The present invention relates to a pressure medium tight inductive pickup for a fluid control element.
Pickups of the above-mentioned general type are known in the art. One of such pickups is disclosed, for example, in the German Auslegeschrift 2,941,195. In this pickup the primary spool and two secondary spools of the spool body are integrated in a housing of an extruded synthetic plastic material and displaceable on a pressure pipe which receives a magnetic core. For adjusting the zero position of the pickup stroke to the stroke of the fluid control element, adjustment means including two nuts and associated thread on the pressure pipe is utilized. This pickup has the disadvantage in the fact that the adjustment of the housing for adjusting the zero position with the aid of the nuts can be performed in very difficult and time-consuming manner, especially taking into consideration that a fine displacement must be performed to a hundredth of a millimeter. The further disadvantage of this construction is that the pickup has no means for additionally influencing of the steepness of characteristic curve. Especially disadvantageous is that the construction of the housing whose insufficient stability against outer actions affects the exact working process of the pickup.
Another inductive measuring transducer is disclosed is the German Offenlegungsschrift 2,915,595. Here for adjusting the steepness of characteristic curve, a pipe of a magnetic material is provided with a slot extending from its end side. Such a construction for changing the steepness of characteristic curve has the disadvantage in that it is difficult to implement additionally in a pickup with a closed housing. In addition to this, for failure adjustment the length of the slot not further can be shortened. It is also a disadvantage of this construction that in this measuring transducer there is no means for zero position adjustment.